In systems of biological analysis, in particular systems of in vitro diagnosis, it is conventional to use disposable plastic tubes intended for receiving different types of liquid and more particularly biological liquids such as whole blood, serum, urine, cerebrospinal fluid or else joint fluids.
If these tubes can be plugged for transport using conventional hard plastic stoppers, the use of these tubes inside the abovementioned systems obliges the handlers to remove the stoppers before installing said tubes in the machine. This handling entails a potential risk of the handler being contaminated by the liquids contained in the tubes. The handler can likewise pose a source of contamination of the biological liquids and therefore thus vitiate the analysis results.
A solution to this problem consists in using stoppers made of a natural or synthetic rubber-based material, jointly referred to as septums, which allow the passage of a metal needle by piercing due to the rigidity and the sharp edge of this latter and which, as a result of their elasticity properties, close again when the needle is withdrawn. Nevertheless such a stopper is not suitable for pipetting devices using disposable plastic cones. Indeed, due to the large size of its tip, the cone is not able to pierce the stopper, without excessive pressure which is liable to cause the material to deteriorate.
Other devices have been developed to allow the passage of plastic cones and a fortiori metal needles to pass without unscrewing the stopper.
Mention can be made of stoppers of the “cross-slit valves” type, such as those produced by the companies Minivalve (CR 150.001, CR270.001 . . . ) and Vernay (VA4394, VA5904 . . . ). These stoppers are originally designed to allow the passage of a trocar. These stoppers are injected and then cut in a cross.
These stoppers are very often made of silicone or cross-linked rubber. The deployment of silicones or rubbers necessitates specific production methods, in order to allow the cross-linking of the materials directly in the mould. This leads to not insignificant elongation of the turn-around time. Finally, if a resumption of machining is necessary, such as a cut-out in the produced item (such as a cross-shaped cut-out in the base of the stopper), this has a direct impact on the manufacturing cost and therefore the cost price of the product.
These same problems also present themselves with the similarly designed devices as with the valves of the “cross-slit” type or of the “duckbill” type, which are used to transfer a liquid between two distinct volume spaces.
Furthermore, these prior art valves based on the principle of deformation of a flexible material have the same problem, namely a limited free passage which is proportional to the flow, but which leads to significant losses of load.
There are other types of stoppers made of several assembled or co-injected pieces. There is generally an elastomer central part and a peripheral made of hard thermoplastic, this latter allowing the stopper to be fixed by clipping or screwing onto the device to be sealed.
However, the two-material injection (or co-injection) is a technologically hard method, which in particular requires special moulds and special injection-moulding machines. The items thus produced are therefore clearly more expensive than those produced through mono-injection. Furthermore, the assembly is an extra step which also contributes to raising the cost price of the product.
All of these devices, stoppers or valves, are thus expensive to produce for the disposable consumable market. Indeed, a consumable is often used only once in biological analysis. As a consequence, its industrial cost price must be as low as possible.
The document EP-A-1 407 820 describes a flapped septum intended to be positioned on a tube. The flap made of plastic is connected to a circular joint by means of a leaf spring. The flap which is oblong-shaped whereas the section of the container is itself circular, impedes a complete lifting of the flap. Such an architecture thus confers a limited fluid-tightness upon said flap. Which can be a major disadvantage in certain uses in which fluid-tightness is a crucial element.
The document GB-A-2 342 427 describes a pipe having a flap which is attached to the pipe by means of a hinge which is presented in the form of a strip which is deformed when the flap is positioned at the end of the pipe. The flap also has a loop on its peripheral part which fixes on a lug arranged on the outer wall of the pipe, and prevents the flap from becoming detached from the pipe. The architecture allows the flap to move away from the tip of the pipe because of its flexible structure to allow a liquid which flows in the pipe to exit from this latter. Nevertheless, such a flap architecture is by no means suitable to be positioned on a container which it is necessary to have penetrated by a pipetting device.
It can be seen from this state of the art that there is no stopper which combines both practicality and ease of use, and which, particularly when positioned on an analysis tube containing a liquid sample, makes it possible to be able to easily take a fraction from the sample using a pipetting device; this is combined with a simplicity of design which does not entail prohibitive production costs and therefore a cost price which is incompatible with a single use.
It also emerges from this state of the art that there are also no valves which are practical and simple to use, combining a full opening and an effective non-return flap system, such valves having to have a limited production cost which is compatible with single use.